Temperature dependence of the conductive layer thickness at the LaAlO3/SrTiO3 heterointerface

By comparing the in-plane and out-of-plane orbitally dependent magnetoresistance under a magnetic field of 9 T, the conductive layer thickness of the LaAlO3/SrTiO3 interface is determined for temperatures between 45 and 300 K. As the influence of spin-orbit coupling cannot be ignored when considering the conductive layer thickness dependence at temperatures below 45 K, a lower magnetic field is employed. The results show that the thickness increases gradually and then remains constant as the temperature decreases. Such a tendency is well reproduced theoretically by considering the equilibrium between drift and diffusion of electrons near the interface. We discover that the thickness mainly depends on the relative permittivity of SrTiO3 and electron mobility, and it is independent of the sheet carrier density. Our investigations show that the dimensionality of the confined zone for electrons can be controlled and can be used as a reference for other interfacial systems in condensed matter physics.